1. Field of the Invention
The present invention relates to a flying head slider in general employed in a recording disk drive such as a hard disk drive (HDD), and in particular, to a flying head slider comprising a slider body, an air bearing surface (ABS) defined on the slider body, and a support projection defining the tip end higher than the level of the air bearing surface.
2. Description of the Prior Art
A flying head slider is well known in the technical field of magnetic disk drives or magnetic data storage systems, for example. The flying head slider is designed to fly above the surface of the magnetic recording disk when the flying head slider receives an airflow, induced along the surface of the rotating magnetic recording disk, at an air bearing surface. Such flying head slider is often seated on the surface of the magnetic recording disk when the recording disk drive is out of operation, namely, the magnetic recording disk stands still. This is called a contact start stop (CSS) control. In the CSS control, the flying head slider suffers from adsorption induced between the flying head slider and the lubricating agent or oil spread over the surface of the magnetic recording disk. The adsorption sometimes obstructs the rotation of the magnetic recording disk. The magnetic recording disk cannot even start rotating.
A flying head slider is proposed to comprise support projections or pads formed on the air bearing surface opposed to the surface of the magnetic recording disk. The support projections serve to keep the air bearing surface above the surface of the magnetic recording disk when the magnetic recording disk stands still. The flying head slider thus contacts the magnetic recording disk over a less contact area. Less adsorption from the lubricating agent may act on the flying head slider seated on the magnetic recording disk.
It is a trend in the field of magnetic disk drives to employ a so-called Hall-less motor as a spindle motor for driving the magnetic recording disk. No Hall element is employed in the Hall-less motor. The Hall-less motor accordingly controls the amount of rotation for the rotor without monitoring or detecting the rotational angle or position of the rotor. The Hall-less motor sometimes suffers from a reverse rotation of the rotation axis when the rotor starts rotating.
The aforementioned flying head slider takes an inclined attitude during flight, making the outflow end or trailing edge closer to the surface of the magnetic recording disk. Accordingly, it is necessary to position the support projections far from the outflow end of the slider body so as to prevent collision between the support projections and the magnetic recording disk during the flight. Such disposition of the support projections causes inclination of the slider body about the tip ends of the support projections when the magnetic recording disk makes a reverse rotation at the beginning of the rotation. The inclination causes the slider body to contact the surface of the magnetic recording disk at the outflow end in addition to the support projections. The effect of meniscus between the slider body and the magnetic recording disk is intensified so that a larger adsorption is caused between the slider body and the magnetic recording disk. The magnetic recording disk sometimes cannot even start rotating in this situation, because a recent spindle motor transmits less torque to the magnetic recording disk.
It is accordingly an object of the present invention to provide a flying head slider allowing a recording disk to normally start to rotate even when a spindle motor causes a reverse rotation.
According to a first aspect of the present invention, there is provided a flying head slider comprising: a slider body; a transducer protection layer superposed on an outflow end of the slider body; a transducer element embedded in the transducer protection layer so as to expose its tip end at a medium-opposed surface; and an adsorption prevention protrusion formed on the transducer protection layer so as to swell from the medium-opposed surface.
The flying head slider of this type often comprises support pads or projections defining the top ends higher than the level of an air bearing surface defined on the medium-opposed surface, for example. The support projections serve to keep a space between the air bearing surface and the surface of a recording medium or recording disk when the flying head slider is seated on the surface of the recording disk. The air bearing surface fails to contact the surface of the recording disk, so that the contact area can be reduced between the flying head slider and the recording disk. The flying head slider may receive less adsorption or effect of meniscus acting from a lubricating agent or oil or water spread over the surface of the recording disk.
When the flying head slider inclines downstream around the tip end of the support projection in response to a reverse rotation of the recording disk, for example, the flying head slider allows the adsorption prevention protrusion to first contact the surface of the recording disk at the outflow end. Enlargement of the contact area can be avoided between the flying head slider and the recording disk to the utmost. The adsorption or effect of meniscus cannot be intensified between the flying head slider and the recording disk. Less torque of a spindle motor, connected to the recording disk, still allows the recording disk to normally start rotating.
The adsorption prevention protrusion is preferably opposed to a step defined between the slider body and the transducer protection layer at the medium-opposed surface. A groove defined between the adsorption prevention protrusion and the step serves to suppress a lubricating agent or water to be sucked between the flying head slider and the surface of the recording disk. Less adsorption from the lubricating oil or water may act on the flying head slider seated on the surface of the recording disk. Less torque accordingly allows the recording disk to smoothly start rotating without hindrance of the adsorption or effect of meniscus.
In recent years, there is a greater demand to reduce the distance between the transducer element and the surface of the recording disk during flight of the flying head slider so as to further increase the storage density of the recording disk. Such reduction in the distance between the transducer element and the recording disk cannot be achieved without a thinner protection layer, such as a DLC layer, laminated all over the medium-opposed surface, for example. On the other hand, the surface at which the transducer element exposes its tip end is preferably covered with the protection layer of a larger thickness. If the tip end of the transducer element is covered with the adsorption prevention protrusion, a thicker protection layer over the tip end of the transducer element can be achieved while keeping a thinner protection layer laminated over the medium-opposed surface. The transducer element may reliably be protected from corrosion and electrostatic destruction or damage.
Furthermore, according to a second aspect of the present invention, there is provided a flying head slider comprising: a slider body; a support projection disposed on a medium-opposed surface of the slider body so as to define its top end highest in an area upstream of a center of gravity of the slider body; a group of protrusions disposed on the medium-opposed surface of the slider body so as to define top ends, lower than that of the support projection, highest in an area downstream of the center of gravity of the slider body.
The flying head slider of this type reliably prevents the relatively higher support projection to collide against the surface of a recording disk during flight even if the support projection is located near the inflow end. The flying head slider also reliably prevents the relatively lower protrusions to collide against the surface of the recording disk during flight even if the protrusions are located near the outflow end. When the flying head slider is seated on the surface of the recording disk, the support projection is designed to support the slider body at the area upstream of the center of gravity above the surface of the recording disk, while the protrusions are likewise designed to support the slider body at the downstream of the center of gravity. The support projection and the protrusions in cooperation serve to stabilize the attitude of the flying head slider. In case where the recording disk starts rotating, the flying head slider hardly changes its attitude on the recording disk. Even when the recording disk makes a reverse rotation as described above, the adsorption or effect of meniscus can be maintained constant between the flying head slider and the surface of the recording disk.
If the height of the support projection is set larger than that of the protrusions, the flying head slider seated on the surface of the recording disk may take an inclined attitude with the inflow end far from the surface of the recording disk. Only the area around the outflow end suffers from the adsorption or effect of meniscus. However, the protrusions serves to reduce the contact area between the flying head slider and the recording disk at the outflow end, so that the adsorption or effect of meniscus cannot be intensified between the flying head slider and the recording disk. The recording disk may smoothly start rotating.
A laser beam may be employed to form the respective protrusions. Tiny bumps formed by laser beams correspond to the respective protrusions. A laser beam serves to form a tiny bump of a smaller diameter and a lower height as compared with the support projection which is in general formed by sputtering or deposition. It is preferable to form an Nixe2x80x94P layer or the similar layer over the medium-opposed surface of the slider body prior to radiation of laser beams.
In addition, the protrusions are preferably arranged in a plurality of rows in an upstream direction. When the flying head slider keeps an inclined attitude as described above, the flying head slider may suffer from abrasion growing upstream form the outflow end because of a friction between the flying head slider and the surface of the rotating recording disk. If the protrusions are arranged in the upstream direction in the aforementioned manner, the protrusion upstream of the abraded or removed protrusion still allows the tip end to contact the surface of the recording disk. Such continuous emergence of the upstream protrusions behind the abraded or removed protrusions serves to maintain a constant space or gap between the flying head slider and the surface of the recording disk. Even when the abrasion keeps progressing on the flying head slider, the adsorption or effect of meniscus cannot be intensified between the flying head slider and the surface of the recording disk.
It should be noted that the flying head sliders of the first and second aspects may be employed in a magnetic recording disk drive such as a hard disk drive (HDD), a magneto-optical disk drive, a similar recording medium drive or data storage system, and the like.